Studies are currently being carried out on two cell lines in culture. C-1300 neuroblastoma cells and C-6 astrocytoma cells are used to investigate differences, if any, between the metabolism of cells derived from glial or neuronal origin. The regulation of cyclic nucleotide concentrations in the cells and the fluctuation of these compounds in response to hormones and/or drugs is under investigation. C-6 cells respond to norepinephrine and C-1300 cells respond to prostoglandin E1 in that adenylate cyclase is activated and the levels of cyclic AMP increase. The calcium ionophore. A 23187, increased cyclic GMP in the C-1300 but not the C-6 cells. The efflux of cyclic nucleotides from the cells into the external medium was determined. A study of the effects of glucose deprivation and/or anaerobiasis has also been undertaken. GABA shunt metabolites and enzymes have been measured in mouse brain and glial and neuronal cells in culture. Anticonvulsants and convulsants were tested for their effects on the GABA shunt in mouse brain and in the cultured cells.